Field effect transistors (FETs) that are formed on a bulk substrate utilize a punchthrough stopper to isolate the device from the substrate. In contrast, semiconductor-on-insulator (SOI) FETs utilize an insulator layer to provide isolation between the device and the substrate. Both the SOI devices and the devices formed on a bulk substrate have advantages and disadvantages. It is therefore desirable to have improvements in field effect transistors that can combine advantages of both types, and reduce the disadvantages associated with each type.